*Motion *(velocity) is caused and changed by *acceleration*, which is caused by *forces*, which is caused by *interactions *with their momentum. What, then, causes *interactions*? Or more accurately, what *starts* an interaction?

The answer is **energy**!

This **Energy **discipline will enable you to answer questions like ‘how fast will the arrow fly when releasing the crossbow spring?’.

*2nd of 2 courses in the Energy discipline.Meet the other participants in the Energy classroom.*

New properties | |
---|---|

Kinetic energy | $K$ |

Gravitational potential energy | $U_g$ |

Elastic potential energy | $U_\text{elastic}$ |

Work | $W$ |

Heat | $Q$ |

Power | $P$ |

New mechanisms | |
---|---|

Kinetic energy | $$K_\text{trans}=\frac 12 mv^2$$ |

$$K_\text{rot}=\frac 12 I\omega^2$$ | |

Potential energy | $$\vec F=-\nabla U$$ |

$$U_g=mgh$$ | |

$$U_\text{elastic}=\frac12 k\Delta L^2$$ | |

Work | $$W=F\Delta s$$ |

Work-energy theorem | $$W_\text{all}=\Delta K$$ |

Energy conservation law | $$E_1+W+Q=E_2$$ |

Power | $$P=\frac{\mathrm dE}{\mathrm dt}$$ |

New phenomena | |
---|---|

Energy | $$E$$ |

Equilibrium | $$\sum \vec F=0$$$$\sum \vec \tau=0$$ |

No-energy rolling |